In the classic model of immune system response, naive effector T cells differentiate into two kinds of cells that combat antigens. T helper type 1 (TH1) cells clear intracellular pathogens, while T helper type 2 (TH2) cells control certain parasitic infections. In 2005, Casey Weaver's team at the University of Alabama at Birmingham identified a third class of T helper cell that produces the cytokine interleukin 17 (IL-17) in response to autoimmune tissue injury, which they named TH17 cells.
Weaver's team was trying to explore the relationship between TH1 and IL-17; IL-17 had been identified years earlier, but its exact role in immune signaling was unclear. By blocking interferon-γ (IFN-γ) - a cytokine essential for the differentiation of TH1 cells from naive T cells - TH1 differentiation was blocked, and instead the team detected the secretion of IL-17. This suggested that IL-17 could not have been produced in the presence ...
